To provide further evidence that carcinogenesis is a consequence of somatic mutation, in addition to that already provided in the progress report, by completing preliminary data already obtained on: a) Comparison of malignant transformation and mutation in simultaneous experiments. b) Phenotype of cells transformed by carcinogens of the frameshift mutation inducing class. To investigate the number of genes which are targets for transforming mutations. To investigate if the transformed phenotype induced by chemical carcinogens is dominant or recessive. To attempt to identify the proteins which are the product of the genes involved in transformation. To investigate further the mechanism of inhibition of postreplicative DNA repair in enhancing transformation frequency.